In dental diagnosis and treatment, dentists make full use of various handpieces (or instruments), such as a dental air turbine handpiece, a dental micromotor handpiece, a dental scaler handpiece, a dental three-way syringe, a dental mirror, a vacuum syringe, a dental photo-polymerization device, a laser handpiece, and a dental tooth cleaning device, equipped with such tools as a dental drilling tool, a dental plaque/tartar removing tool, a treatment area rinsing tool, a drilling debris/saliva evacuation tool, etc. When performing intraoral diagnosis or treatment by using such handpieces, a shadow-free light separately mounted on a dental unit or the like is turned on, and the diagnosis or treatment is performed on the patient while illuminating the patient's oral cavity with the light.
However, depending on the orientation of the patient and the area to be treated or on the direction from which the clinician such as the dentist works, the oral cavity may not be illuminated sufficiently, making it difficult to observe the treatment area; every time this happens, the position of the shadow-free light has to be adjusted, and the efficiency of the treatment work thus suffers.
In view of this, in recent years, a dental handpiece has been developed and commercially implemented that has a light source such as a halogen lamp and a light guide built into the handpiece body and that is designed to illuminate the treatment area such as a tooth by radiating light produced by the light source from the forward end of the handpiece (refer, for example, to Patent Document 1).
This handpiece is a scaler having a tip at the forward end of the handpiece body; in this example, since the shape and length of the tip differ according to the scaler used, and the position of the tip end is therefore not constant, the light exit end of the light guide is arranged in a ring shape on the forward end of the handpiece body so that the emitted light is not concentrated in one particular direction but spreads out with a certain angle. This requires the light guide to be formed in a special shape, resulting in a significant increase in cost. Furthermore, the structure for accommodating the light guide of such shape within the handpiece body becomes complex, and the manufacturing cost increases. There has also been the problem that the mechanism for holding the light exit end portion of the light guide interferes with the fundamental vibration of the scaler, causing an adverse effect on the vibration characteristics of the product.
In view of the above, there is proposed a handpiece in which one or more light-emitting devices are arranged on the forward end of the handpiece body so that the light for illuminating the treatment target area is radiated directly from the light-emitting devices without using a light guide (refer, for example, to Patent Document 2).
Here, light-emitting diodes (LEDs) that emit white light or semiconductor devices that emit laser light are used as the light-emitting devices to be mounted on the handpiece, and the plurality of light-emitting devices are arranged in a ring on the forward end of the handpiece body in such a manner as to encircle the axes of the tool attached thereto, or the plurality of light-emitting devices are combined into a single light-emitting device unit; further, these light-emitting devices are detachably mounted on the handpiece body.
According to the proposed handpiece design, since the light-emitting devices are used as described above, there is no need to use a light guide, avoiding problems associated with the use of the light guide, such as increased cost, increased complexity of structure, and attenuation of light, while also eliminating the need for cooling the light source; as a result, a dental instrument having desired performance can be achieved at a relatively low cost.
In the above-described dental handpieces, the light from the light source is radiated to illuminate the treatment target area in order to facilitate the observation of that area. On the other hand, it is normal practice to radiate light of a particular wavelength to the treatment target area in order to distinguish whether it is dental caries, plaque, tartar, or the like (Refer, for example, to Patent Documents 3 and 4).
The apparatus disclosed in the above-cited Patent Documents is a recognition apparatus for recognizing the condition of a tooth to detect caries, plaque, infection of the tooth by bacteria, etc. with high accuracy and high reliability. The recognition apparatus comprises a light source for generating excitation radiation which is directed to the tooth to be examined and excites fluorescent radiation at that tooth, a detection device for detecting the fluorescent radiation from that tooth, and a spectral filter which is mounted at the front of the detection device, and the wavelength of the excitation radiation to be emitted from the light source is set within a range of 600 nm to 670 nm. With this arrangement, when an increase in the intensity difference between the fluorescence spectrum of the caries region and the fluorescence spectrum of a healthy tooth portion is detected, it is recognized that dental caries is present in the tooth illuminated with the radiation.
On the other hand, various illumination devices have been developed in recent years, aiming to prevent the efficiency of diagnosis or treatment work from dropping due to insufficient intraoral illumination. Many of such illumination devices are designed to be able to illuminate the oral cavity during diagnosis or treatment with a light source mounted on the forward end of the handpiece.
For example, in a contra-angle dental/medical handpiece, a plurality of light-emitting diodes (LEDs) are arranged to encircle a tool mounted in a tool mounting portion so that the area being diagnosed or treated is brightly illuminated over a wide range of 360 degrees around the tool (refer, for example to Patent Document 5). In this handpiece, the power for lighting the plurality of LEDs is supplied via flexible lead wires or a flexible wiring substrate disposed within the handpiece body. However, with the technique disclosed in Patent Document 5, intraoral lesions cannot be detected, because the wavelength of the light emitted from the LEDs is not for detecting lesions; instead, the LEDs are used for simply illuminating the oral cavity.
On the other hand, it is known to provide a dental handpiece which has a built-in light source that emits excitation light capable of detecting lesions; in this handpiece, a laser diode and a light guide are mounted within the handpiece such as a dental scaler, and the oral cavity is illuminated with the light radiated from the forward end of the handpiece and the resulting emission of fluorescence is detected by a photodiode for evaluation (refer, for example, to Patent Document 6). It is claimed that, using this handpiece, the treatment for dental caries, plaque, bacteria infection, calculus, tartar, etc. can be easily performed while detecting such lesions and evaluating them.
With this handpiece, diagnosis or treatment can be done while detecting and evaluating the condition of an intraoral lesion, but it has only been possible to detect and evaluate the presence of caries in the spot area illuminated with the excitation light from the laser diode, and it has not been possible to identify the extent of the caries. Furthermore, the handpiece is not of the type that can be attached to existing dental instruments that dentists use for treatment.
There has also been developed a handpiece of the type in which a light guide and a light source are mounted within the handpiece body so that illumination light for illuminating the oral cavity can be radiated from the forward end of the handpiece, but this type of handpiece is designed to radiate illumination light, not excitation light. Further, in the handpiece proposed in the previously mentioned Patent Document 2, one or more light-emitting devices are arranged on the forward end of the handpiece body so that the light for illuminating the target area to be diagnosed or treated is radiated directly from the light-emitting devices without using a light guide.
LEDs that emit white light or semiconductor laser devices (LDs) that emit laser light are used as the light-emitting devices to be mounted in the above handpiece; on the other hand, there has been developed a dental handpiece that is designed so that a light-emitting device module constructed by integrating a plurality of bare chips each forming an LED can be incorporated as an illumination device for illuminating the intraoral area to be diagnosed or treated (refer, for example, to Patent Document 7). This light-emitting module is provided with electrode pins and, by connecting the electrode pins to a socket provided in the forward end of the handpiece, power for driving the LEDs is supplied via a power cord connected to the rear end of the handpiece.
However, in Patent Documents 2 and 7 also, the light emitted from the light source is illumination light, not excitation light for detecting a lesion, and furthermore, the handpiece is not of the type that can be attached to existing dental instruments that dentists use for treatment. On the other hand, in recent years, the power of LEDs and semiconductor lasers has increased, and it has become possible to observe lesions with the naked eye.
Patent Document 1: Japanese Unexamined Patent Document No. H07-275261
Patent Document 2: Japanese Unexamined Patent Document No. 2000-316874
Patent Document 3: Japanese Unexamined Patent Document No. H05-337142
Patent Document 4: Japanese Unexamined Patent Document No. H09-189659
Patent Document 5: Japanese Unexamined Patent Document No. 2001-112779
Patent Document 6: Japanese Unexamined Patent Document No. 2001-299699
Patent Document 7: Japanese Unexamined Patent Document No. 2002-306512